Dependence of the bilayer phase transition temperatures on the structural parameters of phosphatidylcholines.
Lipids
; 28(5): 365-70, 1993 May.
Article
em En
| MEDLINE
| ID: mdl-8316042
ABSTRACT
Most saturated diacyl phosphatidylcholines C(X)C(Y)PC (saturated 1,2-diacyl-sn-glycero-3-phosphocholine with X carbons in the sn-1 acyl chain and Y carbons in the sn-2 acyl chain), in excess water, can self-assemble into lamellae which, upon heating, may undergo multiple thermotropic phase transitions at well-defined, discrete temperatures. The transition temperature corresponding to the main or the gel to liquid-crystalline phase transition (Tm) is known for many bilayers of fully hydrated phosphatidylcholines. In this study, we have analyzed the Tm values of 44 molecular species of phosphatidylcholines in terms of their structural and packing characteristics in the gel-state bilayer. Two general equations are thus derived Tm = 162.26-3651.71 (1/N) - 88.42 (delta C/N) for C(X)C(Y)PC with X > or = Y, and Tm = 157.68-3525.44 (1/N) - 93.28 (delta C/N) for C(X)C(Y)PC with X < Y. Here, N is the minimal hydrophobic thickness of the dimeric C(X)C(Y)PC in the gel-state bilayer and delta C is the effective chain length difference between the sn-1 and sn-2 acyl chains for the monomeric C(X)C(Y)PC in the gel-state bilayer. The advantage of these two equations in predicting the Tm values for phosphatidylcholines with delta C/CL values in the range of 0.07 to 0.40 is their simplicity. A figure containing a total of 173 calculated Tm values is also presented.
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Base de dados:
MEDLINE
Assunto principal:
Fosfatidilcolinas
/
Temperatura Alta
/
Bicamadas Lipídicas
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
1993
Tipo de documento:
Article